class Task64:
    def __init__(self):
        self.funcs = (self.func1, self.func2)

    def run(self, n):
        return self.func2(n)

    def func1(self, n):
        return 0

    def func2(self, n):
        index = int(bool(n))
        func = self.funcs[index]
        return n + func(n - 1)
